(a) Field of the Invention
The present invention relates to expanded snackfoods such as crisps and like foods obtained by cooking discrete portions of a dough composition.
(b) Description of the Prior Art
An essential requirement to obtain such expanded snackfoods is that before cooking at least some of the starch in the dough should be gelatinized. Gelatinization of the starch is typically achieved by cooking it in the wet state, whence a physical change takes place in its structure such that it becomes more viscous. It is believed the presence of gelatinized starch is necessary to trap the steam produced on cooking so as to give the necessary expanded structure.
Various processes for preparing expanded snackfood products have been described by Willard, Snack Foods, 62, pages 52 to 54, 1973, (see also U.S. Pat. No. 3,997,684) and Matz, Snack Food Technology, The AVI. Publishing Company, Inc., Westport, Conn., U.S.A., pages 144 to 149.
The processes using dough can generally be grouped into three categories and summarised as follows:
(1) The dry collett process:
In this process a thin portion of dried starch-based gel is expanded by a short immersion in hot fat or, as described in British Patent Specification No. 2,008,924 A, by cooking in a hot bed of, for example, salt or calcium carbonate.
Typical of such a process is that disclosed in British Patent Specification No. 888,689 which describes the manufacture of a potato-based foodstuff in which potato flour is mixed with powdered potato starch, water is added to form a dough, and the dough is cooked so as to gelatinize the starch, the swollen dough being dried to form a product having a rubber-like consistency. After drying, the dough can be sliced, the slices further dried, and then cooked in boiling fat to provide potato crisps.
In another such process described in U.S. Pat. No. 4,140,803 starch is gelatinized by feeding an aqueous slurry containing starch onto a hot double roller dryer, and the multilaminar film obtained is cut into small pieces and fat fried.
In other such processes as described in, for example, British Patent Specification Nos. 1,358,097 and 1,484,455, a dough containing some pre-gelatinized starch is extruded through a die under conditions of temperature and pressure which lead to further gelatinization; the small pieces of this dried material are then fried as before.
(2) Frying a wet completely gelatinized dough:
In this process a wet dough containing about 30 to about 85% solids is cut into desired shapes, and then fried, the starch in the dough being completely gelatinized before it is fried. Some of the products made in this category are described in U.S. Pat. Nos. 3,539,356; 3,297,450; 3,451,822; and 4,007,292; and Canadian Patent Specification No. 871,648.
(3) Frying a wet dough containing some ungelatinized starch:
In this process the dough contains a mixture of gelatinized and ungelatinized starch, and consists of from about 30 to about 70%, usually from about 40 to about 50%, by weight of solids. The dough is formed into pieces and fried. With such a dough, for example, as described in U.S. Pat. No. 3,997,684, the expansion is only about 1.6 times the original volume compared with the over three times expansion obtained by the processes of the two previous categories.
In the production of baked or toasted cereal products of the kind used as breakfast foods, and in the production of biscuits and cookies, it is known to employ a dough mixture including bran in various proportions of up to about 100% of the product. Examples of such foods are disclosed in British Patent Specification Nos. 344,055, 1,561,190 and 2,010,656 A.
In addition, British Patent Specification Nos. 1,465,843 and 1,544,843 disclose snackfoods including rice bran material, particularly in the latter case to afford a rice cracker flavour.
Furthermore, U.S. Pat. No. 2,701,200 to Huber, is concerned with a novel puffed product which may contain bran and with a process of producing that product. In the Huber process heated pressure rollers are employed to solve problems encountered in the prior art both with puffing guns and "radiant" puffing, the product produced mainly being a breakfast cereal-type product which is fat- or oil-free. While the earlier disclosure mentions that in place of whole grain materials one may use selected fractions of grains and, as examples of such fractions, selected flours, meals, farina, bran and the like--and indeed while, in its Example 10, the earlier disclosure employs wheat bran and oat bran along with white corn cones and yellow corn cones to give a dry-mix bran content of about 18% by weight--there is no expressed or implied appreciation of the use of added cereal bran in a snackfood product. The presence of bran is incidental to the problem solved by the earlier invention in the provision of heated pressure rollers to achieve a puffed product.
Also, U.S. Pat. No. 3,656,966 to Ball et al, which relates to a process for making a ready-to-eat food chip from cereal grain, includes products prepared by the disclosed process having their own natural bran, that is non-added bran at a level of up to no more than about 9% by weight. It is furthermore disclosed that in the resulting dough the wheat particles of the wheat or rye bran are retained after cooking and it is said that the oil content of the final product may range from about 25% to about 40% and preferably is about 30%. Again, however, the earlier invention is concerned with the use of a cutting operation to reduce the size of individual grain kernels to increase their total surface area and to expose the endosperm, thereby improving the absorption of moisture capabilities of the kernals when combined with water, and not specifically with the provision of a bran-containing food. The presence of bran is again incidental to the problem solved.
Thus, in the prior art, bran-containing products can be seen to fall into one of the following categories, namely:
1. Specialised products with a distinctive flavour e.g. with added rice bran to impart that flavour, PA1 2. Fat-free products e.g. breakfast cereal products, and PA1 3. Products including their own natural bran with relatively high oil or fat contents. PA1 (i) By autoclaving at about 120.degree. C. for about 20 minutes. PA1 (ii) By extruding the bran in a heated extruder which heats the bran to about 160.degree. C. for about 10 seconds. PA1 (iii) By mixing the bran with water to form a slurry, which is then extruded onto a roller dryer operated at about 100.degree. C., followed by milling of the dried product to a fine powder.
Furthermore, it might be thought that to add bran to an expanded snackfood product as opposed say to a breakfast-food product would detract from the degree of expansion or lead to no expansion at all. Also, it might be thought that to add bran would lead to unacceptably high levels of fat or oil, where fat or oil cooking is employed to expand the snackfood dough.
However, I have now found surprisingly that a snackfood can be produced successfully from a dough mix of predetermined volume comprising gelatinized starch and added bran, the snackfood being both expanded to at least about 1.25 said predetermined volume and of relatively low fat content, provided the amylolytic activity of the bran is controlled to prevent breakdown of gelatinized starch in the dough composition subsequent to the formation of the dough composition to be cooked and up to cooking of the dough.